The present invention relates to an apparatus for continuously blanking a coiled metal sheet without blanking parts of welded connection of said sheet, having means for detecting said parts of welded connection, means for cutting said parts of welded connection, and means for removing the cut parts of welded connection.
Generally in a coiled metal sheet, an end part of a metal sheet is lap-welded to an end of another metal sheet when a defect part is cut off from the metal sheet or when the metal sheet is short in length. The parts of such welded connection cannot be generally used as a product even if shaped, and since such parts have a double thickness, the edge of blanking cutter blade will be damaged, if blanked as such, and furthermore processing tools of the successive steps will be also damaged. Thus, the parts of welded connection of a metal sheet must be detected and removed before such parts enter the apparatus for blanking the metal sheet.
One example of such an apparatus for blanking a metal sheet is a cup shaping press, where an operation of the cup shaping press is stopped as soon as a part of welded connection of the metal sheet is detected before that part enters the cup shaping press; the part of welded connection is pulled out manually from said press and cut off by metal scissors; then a cut end of the successive metal sheet is put into the cup shaping press, and then the cup shaping press is restarted. Since the metal sheet has a considerable width, at least two operators are required for said operations, and also there is a risk of damages to hands, etc., because the metal sheet is generally handled manually, that is, by direct touch with hands. Furthermore, a long time is required till the cup shaping press is restarted.